September 2019 was characterised by lower than normal mean sea level pressure over and to the southeast of New Zealand with above normal pressure to the west. This pressure set up resulted in a southwest airflow anomaly across the country (i.e. more southwesterly winds than normal).
Temperature
Temperatures were average (-0.50 to +0.50°C of average) for much of the country despite several cold snaps. Below average temperatures (0.51°C to 1.2°C below average) were observed in a few parts of the South Island including northern Tasman, much of Marlborough, Takaka, and eastern locations between Rakaia and Dunedin. Few isolated locations experienced above normal temperature (0.51°C to 1.2°C above average), mostly in the North Island.
Rainfall
Rainfall was below normal (50% to 79% of normal) over much of the southern portion of both islands (with a few exceptions) with well below normal rainfall (<50% of normal) observed in parts of the Wellington region and for southern West Coast, southwest Canterbury and northwest Otago in the South Island. Above normal (120% to 149% of normal) or well above normal (>149%of normal) rainfall levels were less widely observed, occurring in the Far North, locations between Kaipara and Hamilton (including Auckland), the Coromandel Peninsula, Nelson, and in parts of Otago, Tasman and Marlborough.
Soil Moisture
As of 1 October, soil moisture was near normal for most of New Zealand. Soils were drier than normal for coastal parts of the Gisborne and Wellington regions, and for inland Otago, southwest Canterbury, and a small part of north Canterbury near Culverdon. Wetter than normal soil moisture levels were restricted to very small patches along the east coast of the South Island near Kaikoura, Christchurch and Dunedin.
